Ultrafast, Non‐Equilibrium and Transient Heating and Sintering of Nanocrystals for Nanoscale Metal Printing
Ultrafast, Non‐Equilibrium and Transient Heating and Sintering of Nanocrystals for Nanoscale Metal Printing
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用于纳米级金属打印的纳米晶体的超快、非平衡和瞬时加热和烧结
DOI：
10.1002/smll.202103436
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发表时间：
2021
期刊：
影响因子：
13.3
通讯作者：
Pan, Heng
中科院分区：
文献类型：
--
作者：
Podder, Chinmoy;Gong, Xiangtao;Pan, Heng
在光电子学、光电子学和光电子学中，人们已经深入研究了光电子相互作用过程中的载流子激发、弛豫、能量传输和转换过程。然而，在相对高的激光激发下，导致NC烧结的非平衡加热的研究有限。在这里，作者使用飞秒激光双脉冲相关和原位光透射探测来研究NC的非平衡加热和瞬态烧结动力学。首先，双脉冲相关性研究表明，当两个加热激光脉冲在时间上分开<10 ps时，烧结速率大幅增加。第二，烧结速率被发现增加非线性与激光能量密度时，加热与700 fs的激光脉冲。通过三温模型，提出了电子诱导配体转变介导的NC烧结机理。超快和非平衡过程有助于在干燥（旋涂）和潮湿（溶剂悬浮）环境中烧结。利用烧结速率对激光能量密度的非线性依赖性在NC悬浮液中打印亚衍射极限特征。印刷的最小特征是10200 nm，这是激光波长的1/4。这些发现提供了一个新的角度对nanomanufacturing发展的基础上探测和工程超快传输现象的功能NC。
The carrier excitation, relaxation, energy transport, and conversion processes during light‐nanocrystal (NC) interactions have been intensively investigated for applications in optoelectronics, photocatalysis, and photovoltaics. However, there are limited studies on the non‐equilibrium heating under relatively high laser excitation that leads to NCs sintering. Here, the authors use femtosecond laser two‐pulse correlation and in‐situ optical transmission probing to investigate the non‐equilibrium heating of NCs and transient sintering dynamics. First, a two‐pulse correlation study reveals that the sintering rate strongly increases when the two heating laser pulses are temporally separated by <10 ps. Second, the sintering rate is found to increase nonlinearly with laser fluence when heating with ≈700 fs laser pulses. By three‐temperature modeling, the NC sintering mechanism mediated by electron induced ligand transformation is suggested. The ultrafast and non‐equilibrium process facilitates sintering in dry (spin‐coated) and wet (solvent suspended) environments. The nonlinear dependence of sintering rate on laser fluence is exploited to print sub‐diffraction‐limited features in NC suspension. The smallest feature printed is ≈200 nm, which is ≈¼ of the laser wavelength. These findings provide a new perspective toward nanomanufacturing development based on probing and engineering ultrafast transport phenomena in functional NCs.